1. Field of the Invention
This invention generally relates to a rear suspension structure, and more particularly to a rear suspension whose right and left trailing arms are connected to each other through a torsion beam extending substantially along the width of a vehicle.
2. Description of Related Art
As disclosed in Japanese Patent Laid-open Publication No. 8-324218, a conventional vehicle rear suspension has a twist beam extending substantially along the width of the vehicle to connect a pair of right and left trailing arms, i.e. a torsion beam having a U-shaped section opened toward the front of the vehicle and a curved portion curved upward in the central section. In the curved portion, the radius of curvature is increased from the center toward both ends so that both ends can be linear. This prevents the rear suspension from interfering with a propeller shaft, and increases rigidity of the torsion beam since the curved portion is formed at the center of the torsion beam where a relatively small bending moment is applied.
The conventional rear suspension, however, has problems in that the torsion beam does not have a sufficient strength since it is bent vertically, and that the torsion beam must be increased in weight in order to have a sufficient strength.
It is therefore an object of the present invention to provide a vehicle rear suspension having a pair of right and left trailing arms connected to each other through a torsion beam, the vehicle rear suspension enabling the torsion center of the torsion beam to be arranged in a relatively high position and maintains the strength of the torsion beam at a high level.
The above object can be accomplished by providing a rear suspension comprising: a pair of right and left trailing arms arranged substantially along a length of a vehicle and having front ends thereof pivotally supported by a vehicle body and rear ends thereof supporting wheels; a torsion beam extending substantially along a width of the vehicle and having both ends thereof respectively connected to the right and left trailing arms; and wherein the trailing arms are bent upward in intermediate areas between the front ends and the rear ends such that the trailing arms are bent. It is therefore possible to arrange the torsion beam in a high position.
In one preferred form of the present invention, the respective end portions of the torsion beam are connected to inclining areas of the trailing arms inclining toward the front of the vehicle. In another preferred form of the present invention, the torsion beam extends linearly. In yet another preferred form of the present invention, the torsion beam is opened diagonally downward toward the back of the vehicle. In yet another preferred form of the present invention, the torsion beam has a substantially U-shaped section. Thus, a roll center of the vehicle body extending diagonally downward toward the front of the vehicle via the torsion center of the torsion beam can be inclined at a proper angle. It is therefore possible to easily improve the ride comfort characteristics of the vehicle and properly control the strength of a roll steer. This increases the degree of freedom in deciding the suspension characteristics of the vehicle. Moreover, the strength of the torsion beam can easily be maintained at a high level, and in particular, there is no need for increasing the weight of the torsion beam so as to increase the strength. Further, each trailing arm and each end of the torsion beam are welded together while they are vertically balanced with respect to the torsion center, so that the durability of the strength at the welded part can easily be improved.